The invention relates to a plug-and-socket connection device for the automatic electrical connection of a vehicle trailer, in particular of a semitrailer, to a towing vehicle, in particular to a prime mover, with a socket and a plug that can be mounted on the trailer and the towing vehicle, whereby as the trailer is being hitched to the towing vehicle the plug and socket can be mutually aligned and by means of a drive, e.g. in the form of a piston/cylinder assembly, can be displaced relative to each other between an advanced connection position and a retracted inoperative position. With the aid of the drive, e.g. a cover of the socket preferably opens automatically by displacement of the contact insert which is accommodated in the socket and carries the contact sleeves towards the connection point and closes again when the contact insert moves back into its inoperative position.
A plug-and-socket connection device of this type has already been proposed and the coupling position is supposed to be ensured by sensors. However, because of the usual large tolerances in vehicle building and the risk of the sensors becoming dirty during driving, the exact alignment of the plug with the socket is not that simple. Automatic operation of the coupling process is therefore called into question.